diff --git a/app/src/main/kotlin/com/tutpro/baresip/Config.kt b/app/src/main/kotlin/com/tutpro/baresip/Config.kt
index eacc66f8..5b48017a 100644
--- a/app/src/main/kotlin/com/tutpro/baresip/Config.kt
+++ b/app/src/main/kotlin/com/tutpro/baresip/Config.kt
@@ -138,6 +138,7 @@ object Config {
     fun updateDnsServers(dnsServers: List<InetAddress>): Int {
         var servers = ""
         for (dnsServer in dnsServers) {
+            if (dnsServer.hostAddress == null) continue
             var address = dnsServer.hostAddress!!.removePrefix("/")
             address = if (Utils.checkIpV4(address))
                 "${address}:53"